Slack is great, but it's adoption by popular opensource communities is problematic.

Why? Because opensource communities are on the free plan, which limits search once you have 10k messages. I've had experiences where I wanted to revisit a question I had asked in a Slack channel the previous week, and been unable to find it.

As a result, everyone burns out faster b/c the same questions get asked and answered over, and over.

Couple this with the fact that channels are not indexed by Google and you get a black box where valuable Q&A content and discussion goes to die.

I agree. I am dismayed when I see open source projects using Slack in lieu of IRC or a mailing list. It means I'd be forced to use their awful client (which is slow, buggy, and far too resource intensive for a chat application) or use their awful IRC integration. This is all in addition to the issue you raise of Slack being a black hole beholden to a profit motivated entity.

Just use IRC. It's practically impossible to avoid Slack at any startup now, but I'd love to be able to avoid it in FOSS.

I've been a die-hard defender of IRC and yet, I have been using it less and less since I started using Discord.

I can finally have a single platform for communication. Voice chat, text chat, group chats, friends list, async communication, unlimited logs (no 10k max msg nonsense), webhooks/integrations that let me do far more than IRC bots ever did. All of it under one account. Oh and the client doesn't suck, unlike Slack's. It's fast. The voice quality is superb.

As far as productivity goes, I get far more done with it than I ever did with IRC. The addition of being able to hop on voice very quickly is insanely good. Screensharing and video chat coming this year as well, I'm pretty excited.

It's to the point that I bought Discord Nitro (their premium offering) the day it was released, for no other reason than to give them money.

I hope the question of protocol openness gets resolved; until then, IRC just doesn't cut it for me anymore. IRCCloud.com helps, but their interface is super slow with lots of channels and IRC itself simply has no support for the thousands of improvements that have been made in communications the past 30-something years.

Discord looks amazing but it's marketing materials says it's aimed at gamers and compares the product to Skype, not Slack. I actually joined Reactiflux on Discord today and was pretty confused as to what I had gotten myself into and why the messages where being read aloud in a computer voice.

Short of video calls though, Discord is essentially a drop-in replacement to Slack. We've been using it at my company, it works so damn well. I moved to it for our open source community as well. I use Matterbridge for a three-way mirror between IRC and Gitter as well: https://github.com/42wim/matterbridge/